sql - Oracle SQL - SCD 跟踪随时间变化的属性

Question

我遇到以下错误：

ORA-30483: window  functions are not allowed here
30483. 00000 -  "window  functions are not allowed here"

我试图构建一个水平视图，了解 BOOK_NO 和 WALK_NO 属性随时间的变化。

我认为一种合理的方法是对 Effective_to 日期进行排名，然后将 book_no||walk_no 属性解码为该值......但不确定从这里去哪里！

下面的SQL：

Select METER_PIT_REF 
,MAX(DECODE( RANK() OVER (PARTITION BY METER_PIT_REF ORDER BY EFFECTIVE_TO DESC),1,BOOK_NO||WALK_NO) )
,MAX(DECODE( RANK() OVER (PARTITION BY METER_PIT_REF ORDER BY EFFECTIVE_TO DESC),2,BOOK_NO||WALK_NO) )
,MAX DECODE( RANK() OVER (PARTITION BY METER_PIT_REF ORDER BY EFFECTIVE_TO DESC),3,BOOK_NO||WALK_NO) )
FROM BW_PIT_BOOKWALK_BRIDGE
WHERE BOOK_NO = 'M04'
GROUP BY METER_PIT_REF

任何建议都非常感谢！

Answer 1

使用子查询：

Select METER_PIT_REF,
       MAX(CASE WHEN r = 1 THEN BOOK_NO||WALK_NO END),
       MAX(CASE WHEN r = 2 THEN BOOK_NO||WALK_NO END),
       MAX(CASE WHEN r = 3 THEN BOOK_NO||WALK_NO END)
FROM (SELECT b.*,
             RANK() OVER (PARTITION BY METER_PIT_REF ORDER BY EFFECTIVE_TO DESC) as r
      FROM BW_PIT_BOOKWALK_BRIDGE
     ) b
WHERE BOOK_NO = 'M04'
GROUP BY METER_PIT_REF;

我也DECODE()用CASE. 它与 ANSI 标准等效。